This invention relates to terminal-group-blocked alkyl polyethylene glycol ethers, mixtures of the same with terminal-group-blocked polyglycerol polyethylene glycol ethers, and their use as foam-inhibiting additives in low-foam cleaning agents.
Aqueous cleaning agents intended for use in industry and commerce, particularly for cleaning metal, glass, ceramic and plastic surfaces, generally contain substances which are capable of counteracting undesirable foaming. The use of foam-inhibiting additives is generally necessitated by the fact that the impurities detached from the substrates and accumulated in the cleaning baths act as foam formers. In addition, the use of antifoam agents may also be necessitated by the fact that the cleaning agents themselves contain constituents to give rise to undesirable foaming under the particular working conditions, for example anionic tensides or nonionic tensides which foam at the particular working temperature.
Adducts of alkylene oxides with organic compounds containing--preferably several--reactive hydrogen atoms in the molecule have long been successfully used as foam-inhibiting additives. Adducts of propylene oxide with aliphatic polyalcohols (see German Pat. Nos. 1,280,455 and 1,621,592, corresponding to U.S. Pat. No. 3,491,029 and G.B. Pat. No. 1,172,135, respectively) and with aliphatic polyamines (see German Pat. Nos. 1,289,597 and 1,621,593, corresponding to U.S. Pat. No. 3,463,737 and G.B. Pat. No. 1,172,134, respectively) and also adducts of ethylene oxide and propylene oxide with aliphatic polyamines, particularly ethylene diamine (see German Pat. No. 1,944,569 corresponding to U.S. Pat. No. 3,696,057), have proved to be particularly effective in practice. In addition to a favorable foam-inhibiting effect, alkylene oxide adducts such as these also show the stability to alkalis generally required for use in industrial and commercial cleaners. However, compounds of this class are not sufficiently biodegradable to satisfy many current legislative requirements.